InfraRed and Thermal Cameras, the Solution for Low Light Challenges

Our previous entry, Light - What It Is, and Isn’t, explored the electro-magnetic spectrum and noted what a small portion visible light occupied. While visible light may be small in the big scheme of things, it is the only

type our eyes can utilize for vision.

Cameras also need visible light to capture an image, and they process it in pretty much the same way. There are some species of animals, though, that can function in a minimum of light. The same can be said of certain types of IP cameras, which is a good thing since there are times when it is necessary to capture an event in less than optimal lighting,or even harder, no light at all. As available light decreases, there is a range of surveillance cameras we can turn to.

Low Light IP Cameras  

Owls and cats are both thought of as being nocturnal; a word Merriam Webster defines as active at night. And just what allows these two creatures of the night to carry on life as usual long after the sun has set?  They both have proportionately large eyes; eyes that contain more light receptors than do the eyes of the rest of us, creatures who require a well-lighted situation. Nonetheless, even nocturnal animals need a low level of light. They cannot function in total darkness. The same holds true for low light cameras. They need some light 

A low light camera depends on large image processors to collect as much of the scant light as possible and the CMOS and CCD chips available today are especially good at picking up light. Some low-light color cameras amplify whatever light is available by switching to monochrome mode in order to increase light sensitivity.   

Another way to increase light sensitivity is to choose a lens with a low f number of 1.4 or less. The lower the f number the more light the lens will admit.

IR cameras

When the available light is below the threshold at which low-light cameras operate, we turn to what are also known as day/night cameras. Day/night cameras have infrared or IR sensitivity, meaning they are able to function under infrared illumination.

 The infra in infrared light means below and refers to the fact that infrared light radiates at wavelengths of 700 – 1400 m, a lower frequency than the red portion of light visible to our eyes. Like the rest of the electro-magnetic spectrum, infrared light is always present.

Because infra-red light affects the color capability of  image sensors, day/night cameras are equipped with removable filters to control IR sensitivity. The filters are kept in place during the day but removed at night and the camera switches to mono-chrome mode in which it can utilize infrared light.

Since an I-R camera needs more infra-red light than what occurs naturally, we need to supplement it  Some day/night cameras, like the Vivotek FD-6112V, come with special bulbs or built-in LED IR illumination,

allowing it to function without any other illumination for a distance just over 30 feet. Other I-R cameras require add-on IR illumination. More powerful illuminators are needed for greater distances, and the narrower the beam the better. Some of the more powerful provide a 6 degree beam, lighting as much as 1300 feet. When using IR illumination, we also need to use a lens rated for IR use.

Since infrared light is not visible to the human eye, IR cameras are popular in covert operations when it is necessary that people not know they are being filmed. In extremely covert operations carried out totally dark or conditions impenetrable by light, we can turn to a particular type of IR cameras, those with thermal imaging capability.

Thermal Imaging Cameras

Thermal imaging cameras, technically known as thermo graphic imaging cameras are able to function when there is absolutely no visible light. Thermal refers to the fact that the sensor incorporated into this type of IR camera is sensitive to temperatures higher than the surrounding environment. Thus it can sense the heat radiating from a person

or animal, and can detect this heat energy through conditions such as smoke, fog or blowing sand that would render a  conventional light-dependent camera useless.

Thermal imagine IR cameras are able to function in these conditions because, if you recall from Light - What It Is, and Isn’t, infra-red light radiates at a lower frequency but its wavelengths are longer. The added length allows it to pass through light obstructing particles, off of which,due to its shorter wavelengths, visible light would bounce. The infra-red light penetrates these obscurants, making it possible for the camera’s thermal imager to detect the found object's radiated heat energy.

Thermal imaging cameras are sometimes referred to as FLIR, for Forward Loading Looking Infra –Red

cameras. The name stems from military operations in which planes are outfitted with this type of camera facing forward.

Thermal imaging applications are also used in police forensic work. In fact it was a thermal imaging device that put an end to the search for the surviving Boston Marathon bomber this month. When the owner of a house discovered fresh blood on a tarp covering the winter-stored boat in his backyard, he alerted police. Using a thermal imager, a specially trained officer detected the outline of a cowering figure, and Boston was able to breathe again.

Since thermal imaging promises to play a vital role in our security, our next entry will look at it in more detail, and explore areas and applications that can benefit from its use.

If you would like more information on any of the cameras discussed here, visit www.kintronics.com or fill out out a request for information form and one of  our sales engineers will respond. Or if you'd prefer, call 914-944-3425 

Light - What it Is, What it Isn't

We have devoted several blogs to exploring the interaction between light and image sensors in IP camera technology.It can be boiled down to four words -  light is a necessity. But what are we to do when light is low or practically non-existent? We turn to Infra-red (I-R) cameras.  As the name suggests, I-R cameras make use of infra-red light which lies just beyond visible light in the electro-magnetic spectrum.

In this post, the first in a series that will cover infra-red and thermal cameras, we will start with an examination of the electromagnetic spectrum, the major portion of which does not register with the human eye.

 Let’s start with the portion we are capable of seeing - visible light.

Like an IP camera’s image sensor, our eyes depend on light. They collect this light from the world around us. Everything we see, we see because it is giving off light waves in one of two ways: direct or indirect. Direct sources of light waves include the sun, lamps, and fire. Light waves get to our eyes indirectly when they bounce off an object such as a mirror, a flower, or a human or non-human animal.

 But just because we’re seeing light waves doesn't mean we’re always seeing them in the same color.

Color depends on the interplay of reflected light with the objects it hits, and our eyes’ response to it. The

visible range of light consists of wavelengths measuring from 400 nano-meters to about 700 nano-meters  The wavelengths at the lower end are perceived as purple, while at the upper ends we see red, and in the middle, all the other colors of the rainbow – orange, yellow, green, and blue.  Remember Roy G. BV - the acronym we learned in school to remember the color spectrum?

  But what explains this variety? Remember, light is a form of radiation and can absorbed or scattered, or reflected, refracted or diffracted. What colors we see depend on how objects interfere with the light. And this, in turn, is dependent on the object’s particular physical make-up.  

A green leaf takes on its color because it absorbs five of the six wavelengths of the visible light spectrum except the one occurring at the 500 nano-meters (green), and reflects only that one so that when we look at it, we see

The same process takes place when we see something red,orange, yellow, blue or violet. But what about white and black?  A white object reflects all wavelengths back, absorbing none, while a black object does just the opposite, absorbing all and reflecting none.

This visible light wave spectrum is but a fraction of the electro-magnetic spectrum. The entire spectrum is composed of gamma rays, x-rays, ultra-violet, visible light, infra-red, microwave, and radio waves. Since all are forms of light, whether they are seen or not, they travel at the same speed – 186,000 miles per second.

They differ from each other in their wavelengths and frequency. If we start at Gamma waves on one end and proceed to radio waves on the other we find that the wavelength increases and the frequency decreases.

But how was infra-red light discovered.?

Back in 1799, William Herschel, the German-born British astronomer responsible for the discovery of Uranus and two of Saturn’s moons, was interested in observing sun spots. To this end, he experimented with light filters.  When using a red filter, he found that a lot of heat was being produced. His curiosity whetted, he used a prism and a thermometer to investigate; the prism to break up the sunlight, and the thermometer to measure the temperature of each color of the refracted light.

He found the temperatures were not uniform. Violet had the coolest temperature, and red, the warmest. But

what surprised him most, was finding it was even warmer beyond the red, in an area he could not see.Further experimentation led him to the conclusion that there must be invisible light beyond the visible spectrum. He came up with the name infra-red for this warm portion just beyond red.

Next entry, we’ll look at Infra-red cameras. how they work, and who needs them.

Until then, here’s a question. You may have a device in your living room that sends out infra-red  light. Do you know what it is?


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If you'd like more information on IP cameras visit www.kintronics.com to fill out this information request form.  Sales engineers are also available at 914-944-3425 to answer your questions.